Ethiopia has an explosive HIV/AIDS epidemic with an estimated prevalence of 3.5%. There has been recent evidence that khat (Catha edulis), a locally grown and widely used drug, is associated with sexual activity and unprotected sex. In addition, khat use may be associated with an increase in CD4 T cells in HIV negative individuals. The proposed research will be a cross-sectional survey in three voluntary testing centers located in Addis Ababa, Ethiopia. The main research aims for this study are (1) to describe the pattern of khat use among adult Voluntary Counseling and Testing (VCT) clients in Ethiopia, through qualitative methods, (2) to examine the association between khat use and HIV status among adult VCT clients in Ethiopia, and (3) to examine the association between frequent khat use and CD 4 T cells in HIV negative individuals, after controlling for tobacco use. In depth interviews and focus groups will be conducted in the first few months of the proposed study to guide the development of a questionnaire and address the first research question. This will be followed by survey implemented through face-to-face interviews with consenting subjects aged 18-44, utilizing the VCT centers. Urine and blood samples will also be collected to measure khat exposure and quantity CD4 T cells respectively. In Ethiopia, which has the 5th largest HIV infected population, it will be important to know how khat chewing habit is linked to the spread of the disease. The use of khat is widespread (30-50% prevalence) and it has deep roots in the social and cultural tradition of Ethiopia. Information from this study can aid HIV/AIDS policy makers and programs to address the habitual use of khat as part of intervention efforts in preventing the spread of the epidemic. The outcome of such an investigation will also enhance our understanding of how khat may play a role in determining CD4 T cell count in HIV negative individuals. Project Narrative: A better understanding of the association between khat use and HIV status can aid HIV/AIDS policy makers and programs to address khat use in preventing the spread of the epidemic. In addition, CD4 T cells have been used as a measure of immune status in individuals infected with HIV. Many of the immunological disturbances observed among patients infected with HIV are related to the decline in CD4 T cell counts and percentage during the course of infection;if among HIV positive individuals, khat chewers have a different CD 4 T cell profile than non- chewers, they may require different management guidelines for chemoprophylaxis of opportunistic infections or antiretroviral therapy.